@JoshuaDrake, I agree with you, I've live and worked all over the US, primarily in the South, and I've never heard anyone use the phrase "ruckus room"
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KevinApr 6 '12 at 18:54

All the answers are good, but I'm opting for this one as the best compromise between me & my brother (we've decided we're both right, but he's more right than me). It's the phonemic associations of rumpus (rumpy-pumpy, etc. - playful) as opposed to ruckus (raucous, wreckage, etc. - noisy & potentially violent).
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FumbleFingersApr 7 '12 at 14:05

Both rumpus and ruckus (along with fracas and ruction) are nonce words for, as you say, "any disturbance/commotion". So different people can use them in ways that sound right to them.

However, as we demonstrate here continually, any given thing may, or may not, sound "right" to any given person.

This is where phonosemantics comes in. There is a phonosemantic "meaning" (the quotes indicate it's not quite the same thing of "meaning" as dictionary "meaning") around simplex words (monosyllables like rump, plus one-and-a-half-syllable words like rumpus) containing the rhyme (or rime) /-əmp/

As can be seen from the chart in the link, mostly the -əmp words refer to 3-dimensional objects of about the same size in all dimensions (bump, stump, hump, rump, clump), but there are subsidiary categories, too. The word rumpus sits squarely in the middle of the Pejorative category, with a foot in both the Personal (chump frump grump) and the Aural (crump thump trumpet) subcategories.

I.e, rumpus is predisposed phonosemantically to refer to some unpleasant event that makes a noise -- and was possibly intended to make a noise, and possibly intended to be unpleasant, and therefore potentially involves human conflict. Phonosemantic "meaning" never commands, but it can suggest, and that's why it's all over the place in nonce words.

Not so sure on the whole phonestheme bit, being a part of folk linguistics at least as much as it is of academic. And the "meaning" you attribute to rumpus directly contradicts the word in common American usage.
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user14070Apr 6 '12 at 18:28

@JoshuaDrake or not see my edited answer.
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user14070Apr 6 '12 at 18:34

Fracas seems to be much less of a nonce word than any of ruckus, rumpus, or ruction: fracas, 1727, from Fr. fracas (15c.), from It. fracasso "uproar, crash," back formation from fracassare "to smash, crash, break in pieces," from fra-, aphetic of L. infra "below" + It. cassare "to break," from L. quassare "to shake"
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jwpat7Apr 6 '12 at 18:45

wherever they come from, they can become nonce words if people reach for them first. And, as I pointed out, opinions differ. People all have their own individual senses of how much they use phonosemantic and other cues.
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John LawlerApr 6 '12 at 23:24

To me the words have very different connotations. Rumpus implies physical activity normally associated with playfulness whereas ruckus only has to do with volume and can be pleasant or, more commonly, unpleasant.

A disturbance can be called a ruckus or a rumpus. The difference is with a ruckus you don't know 100% for sure if it is just a disturbance from one source or if there is a reaction to the disturbance from another person or source, since a ruckus can be either one. A rumpus is just a disturbance with out something or someone else joining in to react or oppose . For that reason , a ruckus is used when there is an altercation between two people, and it is seldom used for just a single person causing a disturbance, although it would not be technically incorrect to use it that way .